Where should an AI agent store durable files and notes between sessions?

Short answer: Store them outside the session, somewhere every future session can reach: the repo for notes about code, object storage or a database for large app data, and a shared store such as Fulcra for notes and files that several agents or devices need. In Fulcra, any MCP client or CLI-capable agent reads and writes at a fixed path such as /agents/notes.md, every write is versioned and restorable, and data-updates shows what changed since the last session.

The problem

Agent sessions end, sandboxes reset and context windows fill up. Anything the agent didn't write somewhere durable is gone next time. The usual failure is storage in the wrong place: a temp directory, one machine's home folder, or one tool's memory that the next agent can't reach.

Pick by need

When Fulcra is a good fit

• Several agents (Claude Code, Codex, OpenClaw, a cron job) need the same notes.
• The agent runs in a sandbox or cloud session that doesn't keep its disk.
• You want every write versioned and restorable, and to see which files changed since the agent last looked.

When it isn't

• The notes only matter inside one repo. Commit them; git gives you history.
• You're storing large volumes of app data or need database queries. Over MCP, write_file takes up to 5 MB inline or 30 MB through an upload link. The CLI's file upload has no practical size limit.
• Several agents must write the same file at once with locking. Concurrent writes to one file mean one replaces the other (the earlier version is kept and restorable); there are no locks.
• Nothing needs to outlive the current session.

Other options

• The repo. Free, reviewed, versioned; only reachable where it's checked out.
• Object storage or a database. Scales and fits apps; agents need credentials for it.
• A local folder or synced drive. Simple on one machine; cloud and sandboxed agents usually can't reach it.

1. Write and read at a fixed path:

   uvx fulcra-api file upload notes.md /agents/notes.md
   uvx fulcra-api file download /agents/notes.md -

   Writing to an existing path creates a new version. To roll back, list versions with uvx fulcra-api file stat /agents/notes.md, then run uvx fulcra-api file restore <VERSION_ID>. Fulcra doesn't currently delete earlier versions.
2. At session start, run uvx fulcra-api data-updates "1 day" to see what changed. Counts lag a few minutes, so start the window a little early.
3. For structured entries, create an Event data type once. It prints an ID like Event/<UUID>; use it as <LOG_ID> and check fields with data-type schema <LOG_ID>:

   uvx fulcra-api data-type create Event agent_log --description "Agent run notes"
   uvx fulcra-api record <LOG_ID> -f - <<'EOF'
   {"note": "Finished migration step 3"}
   EOF
   uvx fulcra-api get-records <LOG_ID> "1 week"

4. MCP clients use write_file, read_file, list_files, restore_file and get_data_updates.

FAQ

• Is it free? There's a free tier with 5 GB and no credit card.
• Who can see the files? Only agents you connect, and anyone you share a file with (file share <path> --to <userid> shares its latest version). Shares are read-only; others can never write to your datastore. Data is encrypted and never sold.
• What if an agent overwrites a good file? Restore the earlier version with file restore or MCP restore_file.

Related

• Back up and restore agent memory
• Shared memory for multiple agents
• Share memory between Claude Code and Codex
• Agent context without credentials
• Agent guide: https://www.fulcradynamics.com/llms.txt

Written by Fulcra. We make one of the tools recommended on this page.